Percussive tool operated by internal-combustion engines



Mrch 12, 1946. J. WOHLMEYER PERCUSSIVE TOOL OPERATED BY INTERNAL-COMBUSTION ENGINES Filed Dec. 14, 1940 2 SheetsSheet 1 a w a 6 a3 a W J X 9 5 W 4 H m 1 3 WW3 Ynvenfor: \7o; EF A/o HL ME YER W flftorneys March 12, 1946. WOHLMEYER 2,396,627

PERCUSSIVE TOOL OPERATED BY INTERNAL-COMBUSTION ENGINES Filed Dec. 14, 1940 2 Sheets-Sheet 2 In ventor:

Patented Mar. 12, 1946 PERCUSSIVE TOOL OPERATED BY IN- TERNAL-COMBUSTION ENGINES Josef Wohlmeyer, Berlin, Germany; vested in the Alien Property Custodian Application December 14, 1940, Serial No. 370,141

In Germany December 19, 1939 4 Claims.

Thi invention relates to pile-drivers, pile drawing devices, squarers, rock drills, hammers and the like, and is particularly directed to a percussive tool of any kind which embodies its power supply in the form of an internal combustion engine in the same unit.

The percussive tools of this kind, which have hitherto become known, can only be operated with a relatively small number of strokes per unit of time, as it was necessary to provide long strokes in order to obtain the desired powerful impulses transmitted to the operative tool of the machine. One aimed at increasing the speed of the engine and thereby increasing the efiiciency. To this end the engine has been so constructed that during or at the end of each return stroke an air cushion was created which braked the operative member of the tool in its return movement and thereafter accelerated the same in forward direction. The air cushion, however, proved practically inefiectual. The speed of the engine could be somewhat increased, but not to the extent desired. Besides this the air cushion is disadvantageous as the creation of the air cushion causes a sudden increase of the air pressure; in consequence hereof the stationary or non-operative members of the tool must be very heavy in order to avoid jumping thereof.

The mentioned disadvantages exist also in percussive tools equipped with two combustion chambers whereby the forward stroke as well as the return stroke of the operative tool member is caused by internal combustion. The invention is based on the calculation, that practically the eiliciency of a percussive tool can only be improved by increasing the speed of the engine; by increasing the weight of the operative member of the tool the speed decreases so that practically increasing of the efiiciency cannot be expected. At a definite weight of the operative member of the tool the speed of the engine can only be increased by shortening the stroke.

The invention particularly relates to percussive tools of any kind, whereby, however, the return stroke of the operative member is caused by internal combustion, while the forward stroke is exclusively or essentially caused by an elasticpressure means; it is of no importance, whether the cylinder or the piston of the tool is used as operative member, and whether the fuel is iniected into the combustion space or introduced in a gasified state; finally, the invention is not tied to a special arrangement and construction of the combustion chamber and also not to a special kind of scavenging.

In connection with percussive tools mentioned above the invention consists therein that the pressure of the means acting upon the operative tool member in the direction of the forward stroke is continuously maintained. It is of special advantage if the said pressure is regulable. The pressure means may consist of a spring or of a gaseous pressure medium. In case of a gaseous pressure medium it is recommended to pro-- vide a space which is several times larger than the volume by which it is made smaller by the operative tool member during the return stroke. If the available volume is too small the pressure medium space of the tool may be. connected to a separate pressure medium chamber outside of the tool.

It will, however, be more advantageous to provide a separate compressor or to, combine with the tool an automatic pump the cylinder of which is arranged in or on the stationary respectively non-operative part and the piston of which is arranged in or on the operative member of the tool or vice versa.

The supplemental charge by means of a. compressor or pump is recommendable, aswithout interrupting the operation of the tool-the pressure medium contained in the pressure medium space can be used for starting the tool in a principally new manner. In a corresponding manner the pressure medium can be used for operating the fuel injecting pump or the igniting device and, if desired, auxiliary devices as, for example, the lubricating pump, the water circulation pump etc.

The utilization of the pressure medium for starting the tool may be realized thereby that the operative tool member is provided with a circular face to which pressure medium is admitted in the direction of the return stroke and which is of larger area than the face loaded with the pressure of the gaseous medium. The mentioned circular face may preferably consist of the under face of the scavenging piston.

The pneumatically operated auxiliary apparatuses, such as the injecting pump, the igniting device, the lubricating pump etc., are preferably connected to an intermediate chamber of the non-operative part of the tool, which chamber is alternately ventilated and filled with pressure medium in accordance with the working rhythm of the tool. The advantage of the pneumatical operation compared with the mechanical operation hitherto provided consists therein that the operative mechanism and the operated devices are not afiected by percussive strains.

The invention also comprises the possibility of starting the tool by means of any other disposable gaseous pressure medium provided that it can be admitted in a regulable quantity.

Further features of the invention will be apparent-from the description given hereafter.

In the drawings:

Fig. 1 is vertical section of a pile driver, showing one embodiment of the invention.

Fig. 2 is a view similar to Fig. 1, showing another embodiment of the invention.

Fig. 3 is a schematical side elevation of a complete pile-driver plant.

In carrying my invention into eifect in one convenient manner as, for example, in its application to a pile-driver and as illustrated in Fig. 1 and Fig. 2 I combine the tool with an internal combustion engine of suitable form and construction and operating upon the two-stroke cycle principle and of a power capacity suited to the nature of the work which the tool is required to perform.

The housing i of the pile-driver is provided with a bore 2 serving as combustion space whereby the conventional cylinder head is replaced by a cylindrical extension co-axial with the bore 2 and adapted to take a piston 3 serving as anvil. At the upper end of the combustion space exhaust openings 4 are provided. The operative member of the tool is constructed as a piston of differential diameters; it comprises the percussive piston 5, the scavenging piston 6 and a piston I. The several pistons may be hollow as for example the piston la in Fig. 2.

The scavenging piston works with its upper face 8 as scavenging pump, which introduces the gaseous scavenging medium (air or combustible mixture delivered by a carbureter not shown) through openings or channels 9 into the combustion space 2.

The piston 1 extends into a chamber l0, in which a certain gas pressure is maintained during the whole period of operation. The height of this pressure and the weight of operative tool member are decisive for the percussive power of the tool. Hence the percussive power can be regulated by increasing or lowering the gas pressure.

The lower face ll of the piston 6 is used as means for starting the tool. This face is larger than the face 1b of the piston 1 and 1a respectively so that a differential power in the direction of the return stroke is created if the same pressure fluidnamely the pressure gas in the chamber is admitted to both faces. The admittance of the gas to the face II is controlled by a device comprising a cylinder I 2 and a piston I 3 provided with a circumferential channel. The cylinder I2 is connected through the channel l to the chamber l0, through the channel Hi to the circular space H below the face Ii, and through the channel l8 to the atmosphere. The piston 13 is longitudinally bored, this bore being adapted to take the piston rod I9 which extends through both covers of the cylinder [2. The piston l3 can be raised against the action of the spring 2| by means of a lever 20. The piston rod l 9 is provided at its upper end with indentations 24 through which in the lower position of the piston rod (as shown in Fig. 2) the space 22 above IS with each other. The space 22 is connected to the scavenging cylinder 26 by means of the channel 25.

The piston 6 is provided with a downwardly directed pipe-like extension 21 connected to the chamber in through the channel 28 and guided in the bore 29 of the housing I. The pipe 21 is closed at its lower end by a valve 30 which can be lifted from its seat 33 by means of a rod 32 the position of which can be regulated by a lever 3|. The bore 29 is connected through the channel 34 to a chamber containing a pressure medium and adapted to contain the piston 35 which operates the fuel injecting pump 36 or an igniting device if a combustible gaseous mixture is introduced into the combustion space. A ventilating bore 29a is provided above the valve seat 33.

The regulating rod 31 of the fuel injecting pump 36 is connected to a piston 38 one face of which is loaded by a spring 38 while the opposite face is loaded by the pressure maintained in the chamber ill and transmitted through pipe 40. The spring 39 tends to drive the piston 38 into its position of rest in which a minimum quantity of fuel is injected.

The tools illustrated are provided with pumps which automatically supplement the charge of the chamber H]. In case of Fig. 1 the pump comprises a piston 4I' guided in a corresponding bore 42 of the piston 1. The bore 43 of the piston H is alternately connected through valves 44 to the atmosphere and the chamber 10 respectively. In case of Fig. 2 the charging pump comprises a piston 45 extending from the piston 6 in downward direction and guided in a bore 46 of the housing I. The pump is provided with two valves 48 the upper one of which serves as outlet valve and controls the connection through the channel 41 to the chamber I0.

In the embodiment shown in Fig. 2 a fuel supply tank H and a lubricating oil tank 12 are provided on the upper end of the tool. The cham ber i0 is provided with a charging opening normally closed by an automatic valve 49.

According to Fig. 1 the ignition space is formed by a circumferential groove 50 in the wall of the combustion space 2; in case of Fig. 2 the ignition space is formed by cavities 5! in the piston 5 and the anvil piston 3.

The cooling of the tool is illustrated in Fig. 1.

l The combustion space 2 is surrounded by a cooling jacket 52; the anvil piston 3 is provided with a hollow space 53 connected to the jacket 52 through the opening 54 and to the inlet 53 for the cooling medium through the opening 55. The cooling medium leaves the jacket 52 at 58.

Fig. 3 shows schematically the side elevation of a pile-driver 60 with inlet 56 and outlet 58 for the cooling medium. The flexible pipes, GI and 52 connect the cooling jacket of the tool to a conventional cooler 63. The motor 64 drives the blower 65, the water circulating pump 66 and the compressor 61, these machines being mounted on the compressed air vessel 69, which in turn is carried by wheels Ill. The vessel 69 is charged by the compressor 61 and has open connection with the pressure medium chamber I 0 of the tool.

The service and the operation of the illustrated tools are as follows:

The chamber I0 is first charged with pressure fluid such as compressed air which is admitted through valve 49. Thereafter the piston rod I9 and the piston I 3 are raised into the starting position by means of the lever 20. The pressure medium can now flow from the chamber 10 through the channels 15 and I6 into the circular space l1 and drive the operative tool member 5, 6, 1a upwardly. As soon as the lower edge of the piston 6 slides over the mouth 25a of the channel 25, the pressure medium will flow through the channel 25 into the space 22 and drive the piston l3 downward into its initial position. Hereby the piston l3 can slide over the piston rod l9 due to the elastic ball coupling. The piston rod I 9 is returned into its initial position by the spring 2! as soon as the lever 20 is left free. The space I! has now open connection through the channel 18 with the atmosphere, so that the operative tool member will perform the first working stroke.

By using pressure fluid for starting the tool the pressure in the chamber ID will decrease more or less; in consequence thereof the spring 39 pushes the piston 38 towards its initial position, so that only a reduced quantity of fuel is injected. The working member 5, 6, la thereby is prevented from rising too high due to the reduced counterressure within the chamber l0. As soon as the gas pressure increases the injected quantity of fuel is automatically increased too. Additional hand-operated means for regulating the injection may be provided, if desired.

As soon as the operative member 5, 6, 7a reaches the anvil 3 or shortly prior to this moment the valve 30 is raised from it seat 33 by the rod 32, so that pressure fluid is admitted through the bore 28 and the channel 34 to the piston 35 and drives the latter upward. The pump 36 thus operated injects a certain quantity of fuel into the combustion space. During the combustion the operative member moves upwardly; the pipe-like member 21 moves upwardly too so that the channel 29a becomes free and the piston 35 can return into its initial position, In the same manner a lubricating oil pump can be operated, which preferably is also connected to the piston 35.

During each second stroke, the pump piston 4| of Fig. l or the pump piston 45 of Fig. 2 delivers compressed air into the chamber ll). The pump is so measured that it can supply the maximum air quantity which may be required. The air exceeding the quantity required may be exhausted through conventional automatic pressure valve (not shown).

If desired and particularly in connection with large percussive tools an auxiliary unit as shown in Fig. 3 may be provided.

The motor 64 drives the blower and the water circulating pump 66 of the cooler 63 hereby securing the cooling of the internal combustion engine of the tool. The motor 64 further drives the compressor 61 which supplies compressed air into the vessel 69 connected to the chamber In.

It will be understood that various changes and modifications may be made in the structure herein illustrated and described without departing from the spirit and scope of my invention.

What I claim is:

1. In a percussive tool, the combination of a cylinder; a piston slidable in said cylinder; means to move said piston in one direction by internal combustion of fuel in said cylinder; a second cylinder; a second piston slidable in said second cylinder, and formed integral with said first piston; means to supply a gaseous pressure medium to said second cylinder to move the second piston, and with it the first piston in the direction opposite to that in which it is moved by the said combustion; a third cylinder; a third piston slidable in said third cylinder and formed integral with said first and second pistons; and means to supply the said gaseous pressure medium from the second cylinder to the third cylinder to move the third piston and with it the second and first pistons, in the direction in which the first piston is moved by the said combustion.

2. In a percussive tool in which the working stroke of a reciprocating, operative tool member is produced by the pressure of a gaseous medium, and the return stroke of the said member is produced by the pressure of internal combustion of fuel, the combination of a reciprocating, operative tool member provided with three pistons; three cylinders in which said pistons are slidably mounted, respectively; means to supply the gas eous medium under pressure to one of said cylinders to slide the piston in said cylinder to move the member through its working stroke; means to produce internal combustion of fuel in a second of said cylinders to Slide the piston in said second cylinder to move the member through its return stroke; and means to supply the gaseous medium under pressure from the first cylinder to the third of said cylinders to slide the piston in said third cylinder to move the member into the start position for the working stroke.

3. In a percussive tool in which the working stroke of a reciprocating, operative tool member is produced by the pressure of a gaseous medium, and the return stroke of the said member is produced by the pressure of internal combustion of fuel, the combination of a reciprocating, operative tool member provided with three pistons;

three cylinders in which said pistons are slidably mounted, respectively; means to supply the gaseous medium under pressure to one of said cylinders to slide the piston in said cylinder to move the member through its working stroke; means to produce internal combustion of fuel in a second of said cylinders to slide the piston in'said second cylinder to move the member through its return stroke; and means to supply the gaseous medium under pressure from the first cylinder to the third of said cylinders to slide the piston in said third cylinder to move the member into the start position for the working stroke, the working face of the piston, which moves the member into the start position, having a larger area than the working face of the piston which moves the member through its working stroke.

4. In a percussive tool in which the Working stroke of a reciprocating, operative tool member is produced by a gaseous pressure medium, and the return stroke of the said member is produced by the pressure of internal combustion of fuel. the combination of a reciprocating, operative tool member provided with three pistons; three cylinders in which said pistons are slidably mounted, respectively; means to produce internal combustion of fuel in one of said cylinders, to slide the piston in said cylinder to move the member through its return stroke; means to supply a gaseous pressure medium to another of said cylinders, to slide the piston in said other cylinder to move the member through its working stroke; a conduit connecting said other cylinder with the third cylinder; and control means to control the supply of the gaseous pressure medium from the second mentioned cylinder, through said conduit, to said third mentioned cylinder, to slide the piston in said third mentioned cylinder to move the member into the start position for the working stroke.

J OSEF WOHLMEYER. 

